DE 7811967 UI discloses a drive generating oscillations for processing machines, e.g. an elliptic vibratory screen, to generate real elliptic oscillations, said drive comprised of two circular oscillation exciters generating these oscillations, as well as comprised of different unbalanced weights circulating at the same speed synchronously and in opposite direction. The unbalanced weights are arranged on two through shafts, with a transmission gear being provided in stationary arrangement next to the oscillating part of the machine, e.g. the screen box. The shafts of the unbalanced weights are connected to each other through universally jointed shafts or comparable parts with the transmission gear outlets. The through shafts carrying the unbalanced weights are configured as rigid shafts or universally jointed shafts.
A drive unit attributable to the applicant is comprised of an unbalanced drive to generate linear oscillations of large-size mechanical screens, with the oscillations being excited by so-called double-type unbalanced transmission gears. A transmission gear of this type is comprised of two shafts with unbalanced disks provided thereon, said shafts supported in axis parallel arrangement in a casing and whose oppositely directed movement of rotation is synchronized by a pair of cog wheels within the casing. The unit forms an unbalanced module. One of the two shafts protrudes on both sides from the casing, it is unilaterally driven and via the other shaft end it can drive another unbalanced module of this kind. To achieve a sufficient oscillation rate, this drive unit is comprised of six unbalanced modules mounted on the screen body. These are arranged on cross members in two axis parallel groups. The drive is effected by a non-oscillating stationary unit comprised of an electric motor and a powerful synchronization transmission gear located next to the screen machine. It requires relatively large space on the screen machine and owing to the additional synchronous cog wheels existing in them, as well as due to the oil greasing and the necessarily massively built transmission gear casings, there is an unnecessarily high “dead” mass of the unbalanced modules that oscillates, too.